Diagnosis
You want to classify a BOM item with item category &V1&. The itemcategory is used to link the item to a specific SAP object (such asdatabase table MARA - material masters). If you want to classify theitem, you can only use a class type which is linked to the same objectas the item category (such as database table MARA - material masters).
You have entered item category &V1& and class type &V2&. Since theseare linked to different objects (such as material master and documentinfo record), this is not possible.

Procedure
Please correct your entry for the class type.
If the item category of the item is not correct, you have to delete theitem and create a new item with the correct item category.